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  • TI Thinks Resolved

CCS/DRV8301: No pwm output when nFAULT and nOCTW are high

Prodigy 90 points

Replies: 7

Views: 183

Part Number: DRV8301

Tool/software: Code Composer Studio

Hi all,

Now, I use DRV8301 as gate drivers, however,  when I input the low side pwm signal at pin 22 (INL_C), then I measure the output signal of pin 35 (GL_C), I get nothing.

I only supply PVDD1=18V, PVDD2=0, GVDD=11V, AVDD=6.6V and DVDD=3.348V. The pull high and EN_GATE voltage of nOCTW & nFAULT are 5V. Thermal PAD connects to GND using a DuPont line.

But the nOCTW & nFAULT are 5 and 4.2V. It means there is no fault and warning.

The picture of signal is shown below. (Red is nFAULT, Yellow is nOCTW, Blue is input pwm and Green is output pwm.)

I don't know why the output pwm is when there is no error and warning.

Thanks in advance,

Bojun Wang.

  • Hi Bojun,
    Could you try a couple of things :
    - Are you applying GHC as high as well at the same time ? Could you measure this input ?
    - Read the fault registers to see if you have any faults ?

    thanks
  • In reply to Anuj Narain:

    Hi, Anuj

    I don't input INH_C any signal, therefore, GHC would not output signal.
    Now, I use drv8301 without using SPI interface, so the setting is default.
    Here is a question, the high level voltage of nFAULT is not reliable? So I have to check the registers via SPI?

    Thanks,
    Bojun Wang
  • In reply to Bojun Wang:

    Hi Bojun,
    thanks. No, the nFAULT is reliable but if your pullup is too strong it may overpower the signal. I am assuming you are using the recommended value.
    The other thing I can think of is to check if you are in 3PWM mode instead of 6PWM mode ?
  • In reply to Anuj Narain:

    Hi Anuj,

    Thank you for your response,

    -As mentioned earlier, the pull high voltage of nFAULT is 5 V. Will the power be too strong?
    (P.S. In p8 the test condition of VOH is external 47kOhm connected to 3-5.5 V, dose it matter when I use 5 V connected to 22 kOhm)
    By the way, In the TABLE 3, the mark of Vcc says "Vcc is the logic supply to the MCU", for example, if I use F28069 DSP then the Vcc is 5V right?
    -Due to no SPI controlling, the mode of PWM is default, 6PWM mode, as in TABLE 11.

    Thanks,
    Bojun Wang
  • In reply to Bojun Wang:

    Hi Bojun,
    22KOhm to 5V is fine.
    F28069 is a 3.3V MCU with 4.6V max voltage to my knowledge so please check the d/s for that part.

    It seems like you are doing everything right. Could you check your boards for any shorts or damage or try to replace the DRV8301 IC.
  • In reply to Anuj Narain:

    Bojun,

    I am closing this thread due to inactivity.

    Please post again if needed.

    Regards,

    -Adam
  • In reply to Adam Sidelsky:

    Ok thanks

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